Foot on the gas for air of superiority

Air pollution is one of the biggest risks to public health in the UK, with studies showing it causes more than 40,000 premature deaths per year and that the most deprived areas bear a disproportionate share of poor air quality. A key contributor to air pollu­tion, as well as to 20% of the UK’s carbon emis­sions, is transport, with over half of roadside emissions coming from large vehicles such as buses and heavy goods vehicles (HGVs).

While electrification offers an option for decarbonising smaller vehicles such as cars, putting batteries into larger vehicles presents a challenge due to their size and weight. This is where waste-derived fuels such as biomethane can play a significant role in reducing emissions from these larger vehicles.

Biomethane is a low-carbon, methane-based transport fuel produced from organic wastes and energy crops through anaerobic digestion (AD), a natural process that breaks down organic matter to produce biogas, which can then be upgraded to biomethane. It is particu­larly suitable for fuelling large vehicles such as buses, HGVs, and waste-collection and agricul­tural vehicles. With more than 80 AD plants across the UK producing this green gas, the UK AD industry has sufficient capacity today to produce enough biomethane to power 80% of the UK’s entire bus fleet and the potential to produce enough biomethane to power 75% of all HGVs in the UK.

Given how far hydrogen and electric batter­ies are from being a reliable option for heavy transport, biomethane is a technology-ready, cost-effective means of slashing emissions and particulate matter and improving air quality. Biomethane-fuelled vehicles significantly reduce nitrogen oxide emissions through par­ticulate-matter-free combustion and produce fewer ozone promoters, aldehydes and non-methane hydrocarbons.

The well-to-tank emission values of biome­thane as a transport fuel offer significant car­bon savings whether waste, residue, or crop feedstocks are used. Uptake of biomethane in transport can therefore help the UK achieve its carbon budgets and decarbonisation targets, with the potential to deliver £2.1bn in CO2e savings per year (assuming a carbon price of £100/tCO2e).

Biomethane-fuelled vehicles are quieter than their diesel equivalents, allowing for night-time deliveries that help reduce road congestion. Green gas is also a more robust and simpler technology for reducing emissions and improv­ing air quality than other options, as biometh­ane vehicles are relatively easy to maintain.

A range of bus companies across the UK are increasingly looking at gas buses to improve local air quality, reduce their carbon emissions and save money, with uptake having been stim­ulated by government policies such as the Bus Service Operators Grant and the Green Bus Fund. There may now be as many as 200 biomethane-fuelled buses on the UK’s roads, with companies such as Reading Buses, Merseytravel in Liverpool, Stagecoach in Sunderland, and Arriva in Darlington having adopted biomethane fleets.

In terms of HGVs, six major UK fleet opera­tors (Kuehne + Nagel, Wincanton, Asda, Brit European, Howard Tenens, and Great Bear) are currently trialling 81 gas-fuelled HGVs in what has been described as the UK’s largest biomethane fuel trial to date. Other large com­panies have already begun rolling out biometh­ane trucks – Waitrose, for example, has been operating 12 such trucks since January and is aiming to have a total of 50 in place by the end of the year (see box, right).

As with all other low-carbon solutions, sup­port from government is critical to allowing the market for biomethane to flourish.

The rising of the obligation for renewa­ble-sourced fuels to 12.4% by 2032 in the recently announced reforms to the Renewable Transport Fuel Obligation goes beyond what was originally consulted on and will create a positive investment environment and long-term certainty for renewable fuels that biomethane is perfectly positioned to benefit from.

It is also critical, however, that there is support from central government for the gen­eration of biogas and its upgrading to biometh­ane – without this, the AD industry will be unable to generate biomethane for transport and its many benefits will not be realised. Wider support for AD would not only increase uptake in biomethane as a vehicle fuel but would also provide a host of other benefits including production of renewable energy and biofertiliser, increased food and energy security, and reduced greenhouse gas emissions from wastes.

The opportunity to produce clean, low-cost transport fuel through recycling wastes should be a complete no-brainer for any government – and with the right support the market for green gas will only continue to grow.

At the start of the year Waitrose unveiled its new fleet of 10 compressed natural gas (CNG) powered trucks along with CNG Fuels, supplier of biomethane.

The trucks were described as the ‘most advanced’ fleet in Europe. They use twin carbon fibre tanks to store gas at 250 bar pressure, to increase range from 300 to 500 miles. Scania and Agility Fuel Solutions were credited with jointly developing this ‘game-changing’ technology which addresses concerns about the distance CNG-powered lorries could cover before having to refuel.

CNG Fuels chief executive Philip Fjeld said the high pressure carbon fibre fuel tanks “demolish the ‘range anxiety’ concerns that have made many hauliers reluctant to move away from diesel to CNG”.

Carbon fibre tanks had already been in use in the US and they were adapted and certified for the European market by Agility Fuel Solutions, offering significant advantages over the standard European set-up of eight steel gas tanks. As a result the vehicles are half a tonne lighter, hold more gas and can cover a greater distance.

Each new CNG truck costs 50% more than a diesel equivalent, but these costs are expected to be recouped over two to three years due to the fuel savings they offer. Over their lifetime, the vehicles are expected to save £75,000 to £100,000 and more than 100 tonnes of CO2 a year compared to their diesel equivalents.

Justin Laney, general manager for central transport at the John Lewis Partnership, said: “As well as being quieter, every long-distance lorry we switch from diesel to gas saves as much CO2 as taking 70 cars off the road. This is why we plan to switch more of our trucks to biomethane in the future.”

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